And a second head teacher, Brendan Loughran of Darwen Aldridge Academy, Lancs, says energy drinks brought into his school will now be confiscated.

He has written to parents saying pupils were visibly less able to concentrate after drinking them. In his letter, he said: “There is evidence that the high caffeine and sugar content could potentially lead to health problems.”

Supermarket giant Morrisons has already banned children under 16 from buying them, and X Factor judge Sharon Osbourne has blamed energy drinks for a seizure suffered by her daughter Kelly, 29, last year.

The British Soft Drinks Association said that high-caffeine energy drinks containing more than 150g of caffeine per litre were not recommended for children.